Conventionally, as a pressure control valve to be used in hydraulic circuits equipped on industrial vehicles or the like, a balance piston type one described below with reference to FIG. 6 is known. This kind of pressure control valve V, which is provided between an input port a1c to receive a hydraulic fluid and a tank port a1d to communicate with a tank for holding the hydraulic fluid, contains a main valve part a4 constituted of a main valve element a6 and a valve housing a7 that includes a main valve seat a7a on which the main valve element a6 is able to be seated and a pilot chamber a7b in which the main valve element a6 is put in a slidable manner, and a pilot valve part a5 constituted of a pilot valve element a8 and a pilot valve seat member a9 that is fixed to the main valve part a4 and includes a pilot valve seat a9a on which the pilot valve element a8 is able to be seated. The main valve element a6 is pushed by a pushing means a101 so as to be seated on the main valve seat a7a, the pilot valve element a8 is pushed by a pushing means a102 so as to be seated on the pilot valve seat a9a. Hydraulic pressure in the input port a1c is applied to the pilot valve element a8 through the pilot chamber a7b while both of the main valve part a4 and the pilot valve part a5 are in a closing state.
When the hydraulic pressure in the input port a1c goes up above a predetermined pressure, the hydraulic pressure applied to the pilot valve element a8 exceeds the pushing force of the pushing means a102, the pilot valve element a8 moves apart from the pilot valve seat a9a so that the pilot valve part a5 becomes in an opening state. In this situation, since the inside of the pilot chamber a7b comes to communicate with the tank port a1d, differential pressure between the inside of the input port a1c and the inside of the pilot chamber a7b is generated. If force resulting from this differential pressure exceeds the pushing force of the pushing means a101, the main valve element a6 will also move apart from the main valve seat a7a so that the main valve part a4 becomes in an opening state.
Further, the hydraulic fluid flows in a gap formed between the pilot valve seat a9a of the pilot valve seat member a6 and the pilot valve element a8 while the pilot valve part a5 is in the opening state and the main valve part a4 is in the closing state. The center axis of the pilot valve seat a9a is not always coaxial with the center axis of the pilot valve element a8, and besides the moving direction of the pilot valve element a8 does not always agree with the extending direction of the center axis of the pilot valve element a8. Hence, there is a problem that such a flaw can occur that, when the pilot valve element a8 is eccentric with respect to the pilot valve seat a9a, the pilot valve element a8 vibrates by receiving the hydraulic pressure as the hydraulic fluid flows in the gap and hits the pilot valve seat member a9 generating strange noise.
As a configuration to solve this problem, it is possible to match the moving direction of a pilot valve element to the extending direction of the center axis of the pilot valve element and make the center axis of a pilot valve seat coaxial with the center axis of the pilot valve element by providing a guide body to hold the pilot valve element in a slidable manner (See Patent document 1, for example).
However, the configuration disclosed in the Patent document 1 such that a guide member is separately provided causes another trouble that number of components, assembling man-hours and manufacturing cost increase.